Apparatus for producing nonwoven fabrics

ABSTRACT

APPARATUS FOR PRODUCING NONWOVEN NET FABRIC COMPRISING MEANS FOR WINDING A CONTINUOUS THREAD ABOUT SPACED SUPPORT MEMBERS TO FORM A PLURALITY OF THREAD SECTIONS THEREBETWEEN AND FOR ADVANCING THE SECTIONS IN SPACED, GENERALLY PARALLEL RELATION TO FORM A WEFT SHEET WHICH IS SUBSEQUENTLY COMBINED WITH ONE OR MORE WARP THREAD SHEETS TO FORM A COMPOSITE NONWOVEN NET FABRIC AND CONTROL MEANS FOR SENSING THE PRESENCE OF THREAD SECTIONS IN THE WEFT SHEET AND FOR STOPPING THE WINDING   AND ADVANCING MEANS IN RESPONSE TO AN ABSENCE OF ONE OR MORE SECTIONS FROM A SPACED POSITION IN THE WEFT SHEET.

Sept. 28, 1971 M. M. BOLLES APPARATUS FOR PRODUCING NONWOVEN FABRICS Filed Sept. 11, 1969 2 Sheets-Sheet 1 FIG. "I"

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IN VENTOR. MILTON M. BOLLES TTORNEY p 71 M. M. BQLLES 3,608,164

APPARATUS FOR PRODUCING NONWOVEN FABRICS Filed Sept. 11, 1969 2 Shee1'.s--Shee1'. 2

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INVENTOR. MILTON M. BO LLES 3,608,164 APPARATUS FOR PRODUCING N ONWOVEN FABRICS Milton M. Bolles, Spartanburg, S.C., assignor to Deering Milliken Research Corporation, Spartanburg, S.C. Filed Sept. 11, 1969, Ser. No. 857,037 Int. Cl. B32b 31/12 US. Cl. 28--1CL 4 Claims ABSTRACT OF THE DISCLOSURE Apparatus for producing nonwoven net fabric comprising means for winding a continuous thread about spaced support members to form a plurality of thread sections therebetween and for advancing the sections in spaced, generally parallel relation to form a weft sheet which is subsequently combined with one or more warp thread sheets to form a composite nonwoven net fabric and control means for sensing the presence of thread sections in the weft sheet and for stopping the winding and advancing means in response to an absence of one or more sections from a spaced position in the weft sheet.

This invention relates to the production of nonwoven textile fabrics, and more particularly to an improved apparatus for producing nonwoven net fabrics.

In French Pat. 1,208,968 there is disclosed a process and apparatus for the production of textile nonwoven net fabrics wherein one or more continuous threads are wound about a pair of spaced thread support members in a plurality of parallel loops, or reaches, which are moved laterally there-along in spaced relation to form a weft sheet. One or more warp sheets of threads then are brought into contiguous co-planar relation with the moving weft sheet and are adhesively secured thereto to form a composite nonwoven net fabric. These fabrics are widely used as reinforcement in various laminated prod ucts, such as synthetic polymeric sheets and film, paper sheets, and the like, and as a support backing for carpets and multi-part materials such as ceramic or wooden floor tiles. Such fabric may also be used as packing materials, and as screening material for windows, doors and the like.

In French Addition Pat. 79,765 to the above mentioned patent, the disclosures of both of which are incorporated herein by reference, there is disclosed an improved apparatus for forming an nonwoven net fabric wherein the weft sheet is formed by the use of a winding device consisting of a rotating tubular thread guide arm, the outer end of which describes a circular path enclosing a pair of spaced yarn support members consisting of helical springs. The guide arm rotates to wind a continuous thread about the springs, each of which is supported at one end for rotation about its central axis. The springs extend in generally parallel relation and, as the continuous thread is continuously wound or looped about the supported end of the springs to form a plurality of thread reaches or sections therebetween, the end portions of the thread sections fall between the helices of the springs. As the springs rotate, the helices supportably engage consecutive loop ends of the sections to laterally advance the sections along the springs in generally parallel, spaced relation to form the weft sheet.

Located between the outer ends of the springs are a pair of nip rollers which engage the moving sheet of weft threads as it leaves the springs and combines the same with one or more sheets of warp threads which are fed therebetween to bring the wrap and weft sheets into contiguous, co-planar relation. The weft sheet is sup- United States Patent ported on or between the moving warp sheet and adhesively secured thereto in a suitable manner to form a composite nonwoven net fabric.

Although the helical support springs provide means for positively advancing the weft threads in spaced relation to form the weft sheet, there are certain problems which arise in the use of the rotating helical springs and the rotating thread guide arm. During rotation of the guide arm and springs, particularly at high operating speeds and/or with springs having closely spaced helices, it becomes ditficult to accurately coordinate or synchronize the rotational speeds of the springs and the thread guide winding arm to insure the positioning of a weft thread section between each helix of the spring. This improper synchronization frequently causes misplacement of the thread sections such that a thread section may not be placed between each helix of the spring during its rotation, but two threads may be placed in the same helix of the spring. Non-synchronization of the rotating guide arm and springs also frequently occurs as a result of the sprocket chain driving the helical springs skipping certain teeth of the drive sprocket at high speed operation. Additionally, vibration of the springs at high speed can cause loosening of the springs on their drive shafts to produce misalignment of the helices of the springs during rotation. Improper placement of the threads in the helices of the springs also can result from variations in windage conditions resulting in variable lagging of the thread behind the guide arm during the winding operation. This misplacement results in nonuniform spacing of the weft thread sections in the weft sheets and corresponding nonwoven fabrics of nonuniform construction.

In addition to the problem of insuring accurate placement of the thread sections between each of the helices of the springs to provide a uniform nonwoven product, it is quite often the case, particularly at high speeds, that the force exerted on the weft thread being wound about the spaced support springs causes the weft thread to break, in which case the machine must be quickly shut down to repair the break and to avoid unnecessary loss of time and materials in production of the fabrics.

It is therefore an object of the present invention to provide an improved apparatus of the type described for producing nonwoven fabrics in which breakage or misplacement of the thread sections in the weft sheet can be immediately detected and the machine stopped for correction.

It is another object to provide an improved apparatus for producing a nonwoven fabric having stop motion means for detecting the absence of one or more thread sections in their proper spaced position in the weft sheet, and for stopping the machine in response to such absence for correction.

The above as well as other objects of the present invention are accomplished by providing a photoelectric sensing device adjacent the path of travel of the spaced thread weft sheet along the length of the spaced thread support means for sensing the presence of the individual thread sections passing thereby to repeatedly reset a time-to-close switch in response to the presence of such thread sections, the closing of which switch activates a relay switch in the power supply line to the drive motor of the winding and weft sheet forming elements to stop the same.

The above, as Well as other, objects of this invention may be best understood by reference to the accompanying drawings in which:

FIG. 1 is a schematic side elevation view of an apparatus for producing nonwoven net fabrics of the type hereinbefore described and incorporating the novel stopmotion features of the present invention;

FIG. 2 is a schematic plan view of the apparatus Of FIG. 1;

FIG. 3 is an enlarged fragmentary elevation view of one of the two helical spring thread support members employed in the apparatus of FIGS. 1 and 2 to form the weft sheet, and further illustrating the position of th detection means of the stop motion device of the p ese invention in relation to the weft sheet formed thereby;

FIG. 4 is an enlarged fragmentary view of a portion of the helical spring support device of FIG. 3; and

FIG. 5 is a wiring diagram showing the relation of the electrical components of the stop-motion device of the present invention.

Referring more particularly to the drawings, FIG. 1 shows a schematic side elevation of an apparatus for continuously forming nonwoven net fabrics which generally includes a thread winding section 10, a weft sheet forming section 12, a warp and weft sheet combining section 14, and a take-up roll 16 for collecting the composite nonwoven net fabric.

As shown in FIGS. 1 and 2, thread winding section includes thread winding means comprising a hollow tubular thread guide arm 20 secured to a hollow central shaft 22 for rotation therewith. Shaft 22 is suitably supported by a support frame 23 for rotation about its central axis and is rotatably driven by a motor 24, the shaft of which is suitably connected thereto by a chain and sprocket drive assembly 26. Guide arm 20 is appropriately counterbalanced for rotation by a weighted arm 30 and during rotation, a continuous thread 32 is continuously passed from a supply package 33 through the hollow shaft 22, radially outwardly through the tubular arm 20 and through a thread outlet 34 in its outer end.

The weft sheet forming section 12 includes a pair of helically configured, elongate spaced thread support members or springs 36, 38 which are of substantially identical construction and are supported at one end thereof on stub shifts 40, 42. Surrounding the supported ends of the springs 36, 38 are conically shaped thread guide members 44, 46, the function of which will be hereinafter described.

As best seen in FIG. 2, stub shafts 40, 42 are rotatably mounted at opposite ends of a cross arm support member 48 which is supported by a bearing 49 surrounding drive shaft 22. The springs are rotated about their respective longitudinal axes by a sprocket chain 50 (indicated in dash lines) drivingly connecting a central sprocket 51 on drive shaft 22 to sprockets 53, 54 on the respective stub shafts 40, 42. To facilitate positional support of the springs suitably supported blocks or stop members 56 (FIG. 1) and 58 (FIG. 3) are positioned beneath the springs and abuttingly engage the same to prevent rotation of the cross arm 48 and springs 36, 38 about the drive shaft 22 during its rotation.

As the guide arm 20 rotates with the outlet 34 there in describing a circular path about the supported ends of the springs 36, 38, the thread strand 32 passes therefrom and is wound in a continuous manner about the springs to form a plurality of reaches or thread sections S therebetween. As seen, the thread passing from the guide arm is laid onto the conically shaped members 44, 46 surrounding the springs where it then slides down the member and into the adjacent space formed by the first helix of each spring. As the springs rotate the thread loops formed at the ends of each thread section S are engaged by the helices and advanced along the springs in spaced, generally parallel relation to form a weft sheet. The relation of the threads in the weft sheet is best seen in FIG. 2 while the manner in which they are engaged by the springs is shown in detail in FIG. 3. As shown in FIGS. 1, 2 and 3, the thread guide arm 20 is displaced at 90 angles of its rotational travel about the springs to show the manner in which the thread 32 is wound there- As seen in FIGS. 1 and 2,- the warp and weft sheet combining section 14 includes a pair of nip rolls 60,62 which are rotatably supported by suitable means, not shown, between the free or open ends of the springs 36, 38. As the thread sections being advanced along the rotating springs 36, 38 approach the open ends of the springs they pass between and are engaged by the nip rolls 60, 62. One or more sheets 64, 66 of warp threads are supplied continuously to the nip portions of the rolls 60, 62 from a suitable source such as warp beams, not shown, and, during their movement therethrough, the warp and weft sheets are brought into contiguous coplanar relation. The combined sheets pass over a guide roller and through an adhesive bath 68 where a suitable adhesive is applied thereto. The sheet thereafter passes about the surface of heated drying rolls 70, 72 where the adhesive is dried and cured to secure the warp and weft sheets together and the thus formed nonwoven net fabric is accumulated on the collection roll 16. Although not shown, one or more of the rolls in the warp and weft sheet combining section 14 may be suitably driven to move the sheets through the apparatus.

To facilitate support and positioning of the weft sheet during its passage through the apparatus, selvage threads 74, 76 are supplied from packages mounted on the cross arm 48 (FIG. 2) and pass through central passageways in the stub shaft 40, 42 and the longitudinal axes of the springs to be positioned within the loop ends of the weft thread sections. T he selvage threads strengthen the conposite nonwoven net product and provide additional support to the weft sheet during its passage through the final sections of the apparatus.

As best seen in FIGS. 1 and 3, the stop motion device of the present invention comprises thread detection means consisting of a photoelectric cell 80 supportably positioned above the weft sheet between the helical springs 36, 38. As can be seen in FIG. 3, photoelectric cell 80 includes light source 81 and a light responsive element 82 positioned such that light from source 81 is reflected back by the presence of the individual thread sections passing along the springs and is sensed by the element. The operation of the stop-motion control means may best be explained by reference to the schematic wiring diagram seen in FIG. 5. The light sensitive element 82 is electrically connected by way of an amplifier 84 to a normally open time-to-close switch 86. The light sensitive element may be of a conventional type such as Clairex Type CL 905 HL manufactured by Clairex Electronics, Inc., and the time-to-close switch may be of a conventional type such as lntermatic Time Delay Switch SS 15222-3 manufactured by Intermatic Company. Switch 86 closes to actuate a solenoid switch 88 which breaks the power supply circuit 90 to the drive motor 24 which operates the winding and weft sheet forming sections 10, 12 of the apparatus.

The time-to-close switch 86 is calibrated to close at a desired time delay unless reset by a signal from the photoelectric cell sensing of a thread section passage thereby. A time delay interval may be employed in switch 86 so that it will close unless reset by the photoelectric cells sensing the presence of the thread section in each and every available section position on the helical springs passing thereby, or it may be delayed to close only after a plurality of unfilled thread section positions have passed the photoelectric cell. Thus, it can be seen by reference to FIG. 4 that when one or more thread sections 92, 94 are misplaced from their normal thread section positions 96, 98 along the length of the springs, the photoelectric cell 80 will fail to sense the presence of the thread sections in their proper position and thereby fail to reset switch 86. The switch then will close to actuate the relay switch 88. Obviously if thread 32 breaks upstream of the photoelectric cell 80, absence of thread detection by the photoelectric cell would also permit closure of switch 86. Automatic closure of switch 86 in the absence of being reset by the photoelectric cell causes relay switch 88 to break the power supply circuit 90 to the drive motor 24 and immediately stop operation of the winding and weft sheet forming section 10, 12 of the apparatus.

Although the weft sheet forming rotatable support members have been shown and described as helical springs, it is obvious that other rotatable members having helical configuration, such as screws, threaded cylinders, helically grooved cylinders, and the like, may be employed to form the weft sheet containing the spaced generally parallel weft thread sections. In like manner, although the sensing device of the present invention is described herein as a photoelectric cell, it is obvious that other sensing means, such as fiuidic pressure sensing devices, etc., may be employed to detect the presence of the individual thread sections forming the weft sheet.

The foregoing drawings and specification have set forth a preferred embodiment of the invention and, although specific terms have been employed, they are used in a generic and descriptive sense only and not for purposes of a limitation, the scope of the invention being limited only by the extent of the following claims.

That which is claimed is:

1. Apparatus for producing nonwoven net fabric including spaced elongate thread support means, means for Winding a continuous strand of thread about said support means to form a plurality of thread sections extending therebetween, said support means including means for advancing said thread sections while maintaining them in spaced, generally parallel positions along said support means to form a weft sheet; and control means including thread detection means positioned adjacent the path of travel of the weft sheet to sense the passage of individual thread sections thereby, and means for stopping said winding and advancing means in response to an absence of one or more sections from a spaced position in the weft sheet 2. Apparatus as defined in claim 1 wherein said Winding means and said thread section advancing means include motor means; and said means for stopping said Winding and advancing means includes electrical means connecting said motor means and said detection means to stop said motor means in the absence of the passage of one or more sections of thread past said detection means in a predetermined time interval.

3. Apparatus as defined in claim 2 wherein said thread detection means comprises a photoelectric cell, and said electrical connecting means includes a time delay switch, and means connecting said photoelectric cell and time delay switch so that said switch is reset by said cell upon the presence of a thread section being sensed thereby.

4. Apparatus as defined in claim 1 wherein said thread support means includes a pair of longitudinally rotatable elongate helical members extending in generally parallel, spaced relation for supportably receiving and transporting said thread sections in spaced relation therealong during rotation thereof, said winding means comprises a rotatable thread guide tube having a thread discharge outlet therein positioned to describe a circular path of travel about said helical members during rotation of the tube to wind the continuous strand of thread about said members for support of the thread in thread sections extending therebetween and said helical members being rotatable to advance said thread sections in generally parallel spaced positions between the helices thereof to form the weft sheet and said detection means including photoelectric cell sensing means positioned between said helical members and adjacent thread sections to detect the presence of the sections passing thereby.

References Cited UNITED STATES PATENTS 3,345,231 lO/1967 Gridge et a1. 156--181 3,390,439 7/1968 Kalwaites 28-1 3,422,511 1/1969 Sequin 281 3,426,553 2/1969 Erb 2821UX LOUIS K. RIMRODT, Primary Examiner US. Cl. X.R. 

